I wonder how BG3 will compare to Rogue Trader (although knowing Owlcat it will be very buggy). Still, I think Owlcats storytelling is generally superior to Larian, although the voice acting and presentation will of course mean that in the eyes of the masses BG3 will always be seen more favorable, not matter what.
Interestingly Owlcat seems to be going into the other direction than Larian when it comes to romances and most characters are not romanceable at all. Which is imo quite fitting for 40K and their background
Storytelling is less hard when you're pulling the content out of an adventure path.